Ben, considering the less than average conditions, you've managed to pull out some detail and structure so credit to you for giving it a go. I have the same filter but never use it on galaxies as I find, like you, the colour always looks a bit odd. I guess under highly light polluted skies, this filter seems the best option. I captured this galaxy a few weeks back using an unmodified canon DSLR and the colours look good. Try adding some more data using a UV/IR cut filter on your modded camera without the CLS ccd filter.
With a rather slow scope ( f9 ) and CLS ccd filter, you are forced to increase your sub length or risk more noise by upping the ISO, so it's a bit tough for you. I have also noticed the sky is brighter than normal despite the moon set and clear skies.
Great effort with a 4 inch by the way.
